It’s difficult to figure out the Kings. Sacramento had lost four of five games and had dropped 13 of 18 after defeating Denver on Jan. 3. Yet the Kings have claimed victories over both Cleveland and Golden State in the past two weeks.

“That’s the high point of us, when we’re all locked in and playing for each other,” Willie Cauley-Stein said. “It’s proven that we can run with anybody and we can lose to anybody.”

The Kings played an inspired second half, outscoring the Celtics 59-43. They held Boston to 39.7 percent shooting and 29 field goals, a season-low for a Kings opponent.

“It was probably our worst loss of the season. But tip your hat to them, they won the contest in every way,” said Isaiah Thomas, who had 26 points and seven assists. Tonight was one of those games you’ve got to forget.”

The Celtics would certainly like to forget the second half when they were outscored 59-43. They shot 5 of 15 and were outscored 31-21 in the fourth quarter, which has typically been Thomas’ time.

Thomas leads the NBA in fourth-quarter scoring and had seven points in the final period against the Kings. Yet he made only one basket and left the game with the rest of the starters with more than two minutes left and the Celtics down by 16 points.

Amir Johnson had 14 points and Al Horford and Smart each had 10 for Boston, who played the opener of their four-game road trip.

Cousins was serving an automatic one-game suspension without pay after he picked up two more technical fouls Monday against Chicago, giving him an NBA-worst 16.

“You hate to talk about it (a letdown with the Kings missing Cousins), but give them credit, they stepped up and totally outplayed us,” Horford said.

The Kings led by six points and hiked the lead to 17 midway through the fourth quarter. Cauley-Stein was a huge factor in the fourth, scoring 10 points, while both Barnes and Collison had seven.

“It’s almost like you’ve got to give a little more to try to compensate with DeMarcus being out,” Kings coach Dave Joerger said. “Our defense was fantastic after the first quarter. They didn’t get in the lane quite as much, and we contested a lot of shots in the fourth quarter.”

STILL LOVING THOMAS

The biggest ovation in pregame introductions went to Thomas, who played in Sacramento for three seasons before the Kings traded him to Phoenix in July 2014.

The diminutive 5-foot-9 guard was the last pick in the 2011 draft, but quickly became a favorite of Kings fans his rookie season.

“I think it will always be like that. The fans welcomed me here with open arms from that first day,” Thomas said. “I showed it (the love) back. It’s genuine.”

TIP INS

Celtics: Avery Bradley (injured Achilles), the team’s second leading scorer, has missed nine straight games and 14 of the last 15 games. He did not make the trip. … Good friends with Thomas, boxer Floyd Mayweather was in a courtside seat. Also at the game was Clemson quarterback Deshaun Watson.

Kings: Ty Lawson strained his left hamstring and didn’t play in the second half. He has an MRI scheduled for Thursday. … Sacramento has a 10-15 record at home, where it had dropped eight of its last 10.